What's the current state of affairs regarding duplicate toolchains? If one follows the suggestions on the PR and installs most things via GHCup and installs stack separately, don't you download and install all GHC versions twice? IIRC, this was the case in the past, but I might be wrong. If that's still the case, some warnings about that might be appropriate on the download page, because this duplication would waste hundreds of GB on disk...